Crystal
3 of the 7 encyclopedias on this shelf carry an entry for Crystal. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
in chemistry and mineralogy, a clear transparent body, which, by the mutual attraction of its particles, has assumed the form of some one of the regular geometric solids, being bounded by a certain number of plane surfaces. A crystal consists of three First, plane surfaces, called are said be similar when parts. faces, which to they are equal to each other and are similarly situated; dissimilar, when they . are unequal or have a different position Second, edges, formed by the meeting of two faces. They are said to be similar when formed by similar faces; dissimilar, by dissimilar faces. Equal edges are formed when the faces are inclined at the same angle to one another; unequal, when they are inclined at different angles. Third, solid angles, formed by the meeting of three or more faces; and in this case also they are similar and dissimilar, equal and unequal angled edges. The chemist procures crystals either by fusing the bodies by heat and then allowing them gradually to cool, or by disring them in a fluid and then absolving stracting the fluid by slow evaporation. The method of describing and classifying crystals (now universally adopted) is based upon certain imaginary lines drawn through the crystal, and called its axes. There are seven of these systems, six of which refer to three axes and one to four, and they are subdivided according as the axes are at right angles not (chinometric). (orchometric) or When the axes are equal and at right angles the system is called isometric. When the angles are right angles, but only two are equal, the system is called tetragonal. When the three axes are at right angles but all unequal, the system is called orthorhombic. The classes are as follows: First, the monometric, regular, or cubic system, in which the axes are equal and at right angles to one another; second, the square prismatic or dimetric system, in which the axes are at right angles to each other, and while two are equal, the third is longer or shorter; third, the right prismatic, rhombic, or trimetric system, in which the axes are at right angles to each other, but all are of different lengths; fourth, the hexagonal or rhombohedral system, which has four axes, three in one plane inclined to each other at 60 degrees, the fourth perpendicular to this plane; fifth, the monoclinic or oblique system, in which two axes are at right angles and the third is inclined to their plane; sixth, the diclinic or doubly oblique system, in which two axes are at right angles, the third oblique to both; seventh, the triclinic system, in which the three axes are inclined to each other at any angle other than a right angle. The power of forming crystals is possessed by a great majority of inorganic combinations whether natural or artificial, and also by a large number of organic chemical bodies. The degree of this capacity varies greatly in different substances, so that certain chemical combinations are found only in crystals, others rarely. Bodies which entirely lack the power of forming crystals or crystalline aggregates are called amorphic. The size of crystals also varies greatly. Some are very large, others are only aggregations of microscopic crystals. The infinitesimally small crystals are called microliths. Crystals grow by the deposit of new horizontal layers / 2 4 3 00000 6 9 8 7 H 13 12 DOAV - 16 17 15 19 2/ 20 23 24 25 26 CRYSTALS No. 1, Octahedron; No. 2, Hexahedron No. 3, Rhombic Dodekahedron; No. 4, No. 5, Triakisicosahedron; No. 6, Icositetrahedron; No. 7, Hexoctahedron; Nos. 8 tion of Hexa and Octahedron; No. 10, Combination of Hexahedron and Combination of Octahedron and Dodekahedron; Nos. 12, 13, 14, 15 and 16, Various of regular systems; No. 17, Derivation of Tetrahedron from an Octahedron; Dodekahedron; No. 19, Deltahedron; No. 20, Hexakisoctahedron or Hexoctahedron Pentagonal Dodekahedron; No. 22, Dyakisdodekahedron or Diploid; No. Protopyramid; No. 24, Tetragonal Deuteropyramid; No. 25, Ditetragonal Pyramid onal combinations. 5 10 14 18 T 22 Tetra - Hexahedron; and 9, Combina- Dodekahedron; No. 11, combinations No. 18, Trigonal ; No. 21, 23, Tetragonal ; No. 26, Tetragon their surfaces, always keeping the characteristic angles exactly the same. Even when the growth of crystals in different directions takes pla place, with unequal rapidity, and distorted forms arise, as is often the case, the law still holds good, the inclination of the adjacent planes and the angles which they enclose are the same. Hence the importance and the value of crystallometry and the science of crystallography or crystalology. Crystals occur with an almost infinite variety of forms-calcareous spar having alone more than 200 forms in more than a thousand different combinations, and some crystals have as many as 300 different sides. But all crystals may be grouped in accordance with certain systems .
American Watchmaker and Jeweler (1892)
A term applied to the glass of a watch case. Crystals for watches were first used between the years 1615 and 1620. CUMMING, ALEXANDER. A celebrated clockmaker of England, who was born about 1732 and died at Pentonville in 1814. He was the author of a book called "Elements of Clock and Watch Work," which he published in 1766. There stands in Buckingham Palace to day a clock made by Cumming for George III., which registers the height of the barometer every day throughout the year. He was paid $10,000 for this clock, and received $1,000 per annum for looking after it.
An Encyclopaedia of Occultism (1920)
Crystal prevails against unpleasant dreams, dissolves enchantments, and is a medium for magical visions. Being bruised with honey, it fills the breasts with milk. Leonardus appears to have indulged a little spite against this beautiful mineral. "The principal use of crystal," he says, "is for making cups, rather than anything else